Tread for a step



FIG. 1 is a top, front, and right side perspective view of a tread for a step according to my new design;

FIG. 2 is a top, front, and left side perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a right side elevation view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The dot-dash broken lines represent boundaries of the claimed design and form no part of the claimed design. The dash-dash broken lines depict portions of the tread for a step that form no part of the claimed design. 

CLAIM The ornamental design for a tread for a step, as shown and described. 